1. Field of Invention
This invention relates to antennas. Specifically, the present invention relates to stripline fed dipole antennas and their associated transformers.
2. Description of the Related Art
Antennas are used in a variety of demanding applications ranging from cellular telecommunications systems to missile systems. Such applications often require very compact antennas that are easily tuned for certain signal environments.
Compact, tunable antenna designs are particularly important in military applications employing antennas for missile guidance. The antennas must often fit in very compact spaces such as radomes. The weight and space requirements of the antenna add design constraints to the missile thereby increasing system cost and may compromise performance.
Often, the antennas are tuned for different signal environments and/or to meet different system requirements such as phase error or antenna sidelobe specifications. To tune a typical dipole missile seeker antenna, the lengths of transformers and feed lines in the antenna are adjusted. The adjustments typically increase the space occupied by the antenna and result in undesirable antenna protrusion into the radome. The excess protrusion may result in less antenna aperture and a corresponding degradation in antenna performance. In addition, the line length adjustments are often ineffective at tuning out junction effects. As a result, in high frequency applications such as Ka band applications, where junction effects can be significant, transformer length adjustments are often ineffective. In addition, line length extension may result in undesirable electrical coupling between feed lines. The coupling may result in undesirable changes to sidelobe levels, null depths, and/or gain losses and a corresponding overall decrease in performance.
Hence, a need exists in the art for a compact tunable antenna for achieving maximum performance while occupying minimal space that is applicable to high frequency applications such as Ka band applications.